It’s not the opening sequence, it’s not a new batch of photos – they’re four scenes from Nickelodeon’s upcoming Avatar: Legend of Korra!
These give you a good look at the animation style and similarities/differences to The Last Airbender.
Avatar The Legend of Korra First Scene by Debris65
Three other just-leaked scenes can be viewed over on io9. What do you think!?
The show will premiere in the Fall.